Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import *
H,W = map(int,input().split())
S = [(W+2)*["#"]]+list(["#"]+list(input())+["#"] for h in range(H))+[(W+2)*["#"]]
S[1][1] = 1
Q = deque([[1,1]])
D = [[1,0],[-1,0],[0,1],[0,-1]]

while Q:
  x,y = Q.popleft()
  for dx,dy in D:
    if S[x+dx][y+dy]==".":
      S[x+dx][y+dy] = S[x][y]+1
      Q.append([x+dx,y+dy])

if S[H][W]==".":
  print(-1)
else:
  print((H+2)*(W+2)-sum(s.count("#") for s in S)-S[H][W])